Speaking From experience if you don't mind spending the extra money run a #2 gauge I made the mistake of running a 60A feed which later found that it wasnt enough then I had to do it all over again. So all I'm saying is make sure you know what you want because once its done it really sucks to have to do it over.
I used #6 so saws and air compressor would run properly. Also ground new servive at out building by sinking a 8 ft copper rod.
10/3 direct bury grade